On the morning of May 12, some of the DML II winners got to visit MLK Elementary in Washington as part of the celebration of National Lab Day. Here's a video of them doing an experiment with some of the students.
Update 5/17/2010: David Gibson, one of the DML winners featured in the video, added the following observation in the comments :
After a morning assembly at Martin Luther King Elementary school in DC, where there was some blah-blah and awards given, and a great lesson on lightening (and what to do when) in front of a a crowded gym, it was good to get outside to capture some really good hot air! The kids were happy, having fun with smiling and laughing adults, in the great outdoors on a fabulous morning in DC, filling up a plastic sleeve. The balloon would have taken off for the sky except that on two or three of the runs to fill it up, it encountered a rose bush and got a few holes. The holes were small enough to just keep it moderately filled, but since the ends were tied, it would have deflated eventually. The kids understood that hot air was causing the sleeve to expand; and they illustrated it by moving and dancing slowly in place for "cold" and then running around like crazy for "hot", which caused them to spread out, just like the hot air does.